FIXITY OF TYPE. 199 



we may invariably reproduce the good characteristics with 

 greater certainty, and in an improved form, in the offspring. 

 If the individual animals be well selected, we shall in every 

 generation gain stronger and stronger hereditary power and 

 permanence of qualities. We shall concentrate the peculiari- 

 ties of the race or breed. But we must avoid, so far as pos- 

 sible, any opposing influences in the parents, as tending to 

 weaken the hereditary tendenc}^ in the young. We are to 

 avoid any thing like crossing with the strictest care. 



With respect to the practice of breeding in-and-in, as it 

 is termed, which comes naturall}^ in this connection, many 

 conflicting opinions have been expressed ; and the general 

 conclusion arrived at is, that it is safe only within certain 

 narrow limits, and then only under the hands of the skilful 

 breeder. 



Breeding in-and-in is commonly understood as an indefinite 

 term applying to any near relationship ; but its legitimate and 

 proper application is to designate animals of the same blood 

 as own brother and sister. But a son is only half the blood 

 of his mother, and a daughter is only half the blood of her 

 father. You may breed such relationship together to a cer- 

 tain extent without injury ; that is, you may put a bull to 

 his mother or to his daughter, and greatly concentrate the 

 hereditary power in the offspring. But even this course is 

 to be followed with care and judgment, and not pursued too 

 far. After reaping the first advantages to be derived from 

 it, the breeder will do well to stop and consider. Breeding 

 in-and-in, i.e., own brothers and sisters, will give a more per- 

 fect form ; but, if carried beyond one generation, it will be at 

 the certain sacrifice of size, and perhaps of the strength of 

 constitution. It greatly weakens the reproductive powers, 

 and often leads to other and still more serious evils. Bear in 

 mind that I refer to own brothers and sisters. More distant 

 relationships can be put together with less risk, of course, 

 and, if carefully watched to discover the least injury to the 

 vigor of constitution, this course may be adopted to some 

 extent where the design is to bring up a pure herd having 

 certain highly important qualities which it is desirable to 

 concentrate and perpetuate. At the same time it should be 

 borne in mind that pure-bred animals have now become so 

 common and so numerous, that it will not be difficult to 



